HydroCAD Stormwater Modeling - Since 1986

NOAA Precipitation Frequency Data Server (PFDS)

NOAA Atlas 14 provides rainfall data for most of the United States.  Follow these instructions to download rainfall data from this site:

1) Open the NOAA PFDS web page at http://hdsc.nws.noaa.gov/hdsc/pfds/

2) Select a state from the drop-down list, or click the state on the map.  Note: NOAA data is only available for the states shown in blue.

3) Set "Data Type" to "Precipitation Depth".  (To ensure full precision, the intensity format is not supported and will not be recognized by HydroCAD.)

4) Units can be English or Metric (HydroCAD will convert as required).

5) Make sure the "Time Series Type" is set to "Partial Duration"

6) Select the exact site location according to the instructions at the right side of the map -or- click the desired location on map.

7) Scroll to the bottom of the page (past the tabular report) and make sure "precipitation frequency estimates" is selected:

8) Click the "Submit" button at the bottom of the page.  If your browser asks to "Open or Save", select "Save".  If the table opens in a new browser window, select File|SaveAs from the browser menu or right-click the table and select "Save As".  (The specific command will vary depending on which browser you're using.)

9) Set the "Save In" or "Save As" selection to your HydroCAD IDF folder or projects folder:

Master IDF folder (32-bit systems) = C:\Program Files\HydroCAD\IDF
Master IDF folder (64-bit systems) = C:\Program Files (x86)\HydroCAD\IDF
Default project folder (all systems) = Public Documents\HydroCAD\Projects

10) Enter a "File name" with an HCI extension, such as "ME-Knox.hci"

You may use any file name you wish, but we recommend this State-Location format for easy file management as your library of rainfall data grows.  The HCI extension is required in order for HydroCAD to recognize this as an IDF file.

11) Make sure the file format (if shown) is set to "CSV", "Plain Text" or "Text Document" and click "Save".

Note:  The exact file save sequence and format options will vary depending on your browser.

12) Close the NOAA window(s).

The rainfall data is now stored in your HydroCAD IDF folder (or HydroCAD project folder), ready for use with the SCS or Rational method, as described here.

Due to an October 2016 change to the NOAA file format, HydroCAD 10.0 build 19 is required to read recent NOAA files.  Opening these files with an earlier build will generate the error "No events present".


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